Question with diagnosing code 13(pressure sensor)
 

Hello,

I have a 91’ NA conversion to a Turbo using S5 NA harness and S5 ECU (N370). It’s still pulling code 13, which is the pressure sensor. The car doesn’t run right when boost builds and the check engine light comes on.

In the shop manual page F2-82, says to test the pressure sensor by applying 100mmHg of vacuum and measure the voltage at the boost sensor plug (G/Y wire) The voltage should measure 1.9V-2.1V. That checks out fine.

But on page F2-78 and F2-25 it says the voltage should read 2.8V-3.2V on the signal wire (G/Y) at the ECU. Since it is the same wire, why does the shop manual give two different voltage specs?

Also I have disconnected the wires going to the instrument cluster that relate to the factory boost sensor.

Could I have a bad ECU or boost sensor?

Did you use the NA or Turbo sensor?

oh, forgot to mention..

N370 pressure sensor (turbo)

Check the vac line for cracks, check to make sure it's plumbed to the right place. Sounds like the sensor itself is shot though. The original one on my NA tested out fine as well, and turned out to be defunct. Luckily it's simple enough to swap out, and there's all of three spots to check for a malfunction. If it's reading fine in vac, your wiring is probably fine.

Here are the scans from the shop manual.. Doesn't make sense to me

Error Code 13 (EC-13) FSM Typo for Turbo
 

I was looking in the FSM and there must be a typo for the Pressure Sensor test voltage in the Turbo (F2) Section.

As you stated:
1) In the shop manual page F2-82, says to test the pressure sensor by applying 100mmHg of vacuum and measure the voltage at the boost sensor plug (G/Y wire) The voltage should measure 1.9V-2.1V. That checks out fine.

2) But on page F2-78 and F2-25 it says the voltage should read 2.8V-3.2V on the signal wire (G/Y) at the ECU. Since it is the same wire, why does the shop manual give two different voltage specs?

1) Seems to be correct for the F2 Turbo section.

2) Probably data from F1-84 the Non-Turbo Section and was mistakenly copied from the Non-Turbo to the Turbo diagnositic section.

So nominal 2.0v @ 100 mmHG of vacuum is for the Turbo pressure sensor application.